Field of the Invention
The present invention relates to an image-forming apparatus that forms an image on a sheet of continuous recording medium.
Description of Related Art
In recent years, an image-forming apparatus has been developed which forms an image on a sheet of continuous recording medium (hereinafter, also referred to as “sheet of continuous”) such as a roll sheet and a performed form sheet. Such an image-forming apparatus contains a feeder that feeds the sheet of continuous paper, a printer that forms or prints the image on the sheet of continuous paper fed from the feeder, a sheet-receiving reel that receives the sheet of continuous paper fed from the printer and a control portion that controls operations of these feeder, printer and sheet-receiving reel. The printer includes an electrophotographic printer, an ink jet printer, a dot impact printer and the like.
For example, Japanese Patent Application Publication 2008-233770 has disclosed that in the image-forming apparatus, when conveying the sheet of continuous paper, any tension is applied to the sheet of continuous paper. In the image-forming apparatus, in order to position the sheet of continuous paper when conveying the sheet of continuous paper, each tension roller is aligned and/or any position correction device such as an edge guider and an edge position controller (EPC) uniformly positions an edge of the sheet of continuous paper. Further, a side guider and/or flanged roller may be used for settling a position of the sheet of continuous paper.
When the sheet of continuous paper is newly set, namely, fed into the image-forming apparatus, any vibration such that the sheet of continuous paper wobbles along a width direction thereof may occur when the sheet of continuous paper is newly conveyed. This is because although a person normally sets the sheet of continuous paper into the image-forming apparatus, it is very difficult for the person to set the sheet of continuous paper at a stable conveying position thereof.
Further, when exchanging parts relating to any variation of the sheet of continuous paper along the width direction thereof in the image-forming apparatus, any vibration such that the sheet of continuous paper wobbles along the width direction thereof may occur under the influence of any tension (conveying pressure). This is because the fixing device has a strong conveying force in, for example, the electrophotographic printer so that the sheet of continuous paper is also conveyed with a strong conveying force and exchanging the relating parts in the fixing device exerts a large influence on the conveyance of the sheet of continuous paper. Additionally, exchanging parts of a secondary transfer portion also exerts a large influence on any variation in the conveying pressure when conveying the sheet of continuous paper, so that any vibration such that the sheet of continuous paper wobbles along a width direction thereof may occur. Still further, when there is a fixing and separation compression operation in the fixing device of the electrophotographic printer, any vibration such that the sheet of continuous paper wobbles along a width direction thereof may also occur similarly because of large variation in the conveying pressure.
These vibrations are damped vibrations of sine wave so that when the sheet of continuous paper is conveyed by a given amount of conveyance, the vibrations stably converge. Accordingly, a past image-forming apparatus has conveyed the sheet of continuous paper while the printer has not printed the image, until the sheet of continuous paper does not wobble to be stably conveyed, in order to form or print the image on a set position of the sheet of continuous paper without moving the image position in the sheet of continuous paper. FIG. 1 shows a past image-forming apparatus 10 having such a mechanism.
The past image-forming apparatus 10 uses a roll sheet 18 as the sheet of continuous paper and includes a printer 12, a feeder 14 that feeds the roll sheet 18 and is positioned at an upstream side of the printer 12, and a reel 16 that is a sheet-receiving device and is positioned at a downstream side of the printer 12. The feeder 14 contains a shaft 20 of the roll sheet 18, a tension roller 22 and a guide roller 24. The printer 12 has a configuration that is similar to that of the past printer. The printer 12, in a case of, for example, the electrophotographic printer, contains exposing devices, photosensitive drums, an intermediate transfer belt, a secondary transfer roller, and a fixing device, which are not shown.
The reel 16 of the past image-forming apparatus 10 contains a reel shaft 26 of the roll sheet 18, a tension roller 30 and a guide roller 28. In the reel 16, a sheet position sensor 32 such as line sensors measures any vibration such that the roll sheet 18 wobbles along the width direction thereof. In the case of the line sensors, the sensors are arranged along the width direction of the roll sheet 18 and measure a position of an edge of the roll sheet 18. The image-forming apparatus 10 checks a measurement output signal from the line sensors and waits until an image position of the edge of the roll sheet 18 does not wobble and becomes stable. When checking that the roll sheet 18 is stably conveyed, the printer 12 forms or prints the image on the roll sheet 18.